In this work, we have investigated temperature dependent electrical transport properties of carbon based two-dimensional (2D) nanomaterials. Various techniques were employed to synthesize the samples. For instance, high quality large area graphene and boron, nitrogen doped graphene (BNC) were grown using thermal catalytic chemical vapor deposition (CVD) method. Liquid phase exfoliation technique was utilized to exfoliate graphene and graphitic carbon nitride samples in isopropyl alcohol. Chemical reduction technique was used to reduce graphene oxide (rGO) by utilizing ascorbic acid (a green chemical) as a reducing agent. Detailed structural and morphology characterization of these samples was performed using state of the art microscopy as well as spectroscopic techniques (for example; Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), UV-Visible spectroscopy as well as Raman Spectroscopy). The low temperature (5 K< T <400 K) electrical transport properties of these materials show substantial difference from sample to sample studied. For instance, CVD grown graphene film has displayed metallic behavior over a wide range of temperature (5 K < T <300 K). At higher temperatures, resistivity followed linearly with the temperature (ρ(T) ~T). A power law dependence (ρ(T) ~ T4) observed at lower temperatures. Where as liquid phase exfoliated graphene and graphitic carbon nitride samples displayed nonmetallic nature: increasing resistance with decrease in temperature over a wide range (8 K < T < 270 K) of temperature. Electrical transport behavior in these samples was governed by two different Arrhenius behaviors in the studied temperature range. In the case of rGO and BNC layers, electrical conduction show two different transport mechanisms in two different temperature regimes. At higher temperatures, Arrhenius-like temperature dependence of resistance was observed indicating a band gap dominating transport behavior. At lower temperatures, Mott's two dimensional-Variable Range Hopping (2D-VRH) behavior was observed.

Made available in DSpace on 2014-06-11T19:32:17Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-02-26Bitstream added on 2014-06-13T19:02:43Z : No. of bitstreams: 1 facincani_ap_dr_jabo.pdf: 858313 bytes, checksum: ed1c0a29bbfb5d008f9e8ca583e52cf0 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A bactéria fitopatogênica Xanthomonas axonopodis pv. citri (Xac) é o agente causal do cancro cítrico, responsável por perdas significativas na citricultura nacional e mundial. Com a finalidade de se obter um primeiro mapa proteômico de referência da Xac, as bactérias foram cultivadas em dois meios não indutores de virulência (meios CN e TS8), e as proteínas foram digeridas com tripsina e analisadas pela tecnologia de MudPIT (Tecnologia de Identificação Multidimensional de Proteínas). Trinta e nove por cento de todas as proteínas preditas pelo genoma da Xac foram identificadas através de seus peptídeos, e estão distribuídas em todas as categorias funcionais. Além disso, 25% das proteínas designadas como hipotéticas conservadas do genoma foram identificadas. Outro objetivo deste trabalho foi analisar o perfil de expressão protéico durante a patogênese decorrente do contato Xac / The phytopathogenic bacteria Xanthomonas axonopodis pv. citri (Xac) is the causal agent of the citrus canker disease, which responds for important losses in national and worldwide citriculture. In arder to obtain the first proteomic reference map of Xac, the bacterium was grown on two non-inductive media for bacterial virulence (CN and TSB media) and proteins were proteolysed with trypsin and analyzed by MudPIT technology (Multidimensional Protein Identification Technology). Thirty nine per cent of ali predicted proteins from Xac genome were identified with their component peptides as belonging to ali functional categories. Besides, 25% of proteins described as conserved hypothetical in Xac's genome were identified. Another aim of this study was to analyze the proteome profile during Xac

Doctor of Philosophy / Department of Plant Pathology / Anna E. Whitfield / The Bunyaviridae is a family of animal and plant viruses that pose a threat to human, animal, and plant health worldwide. In nature, the dissemination of these viruses is dependent on arthropod vectors (genera Orthobunyavirus, Nairovirus, Phlebovirus, and Tospovirus) or rodent vectors (genus Hantavirus). The genus Tospovirus is the only one within this virus family that is composed of plant-infecting viruses transmitted by thrips. Tomato spotted wilt virus (TSWV), the type species of the Tospovirus genus, is one of the ten most devastating plant viruses known. It is most efficiently transmitted by the western flower thrips, Frankliniella occidentalis Pergande, in a persistant propagative manner. The insect molecules associated with virus infection and transmission by the thrips vector remain unidentified to date. The aim of this work was to identify F. occidentalis larval thrips proteins that are differentially expressed during TSWV infection of the insect vector and those that directly interact with TSWV. To achieve these goals, I used two-dimensional (2-D) gel electrophoresis and mass spectrometry coupled with Mascot searches. I identified 26 protein spots that displayed differential abundances in response to TSWV infection, which contained 37 proteins. Sixty two percent of these proteins were down-regulated by the viral infection demonstrating a complex response. Moreover, 8 and 11 protein spots that directly interacted with purified TSWV virions and a TSWV glycoprotein (GN), respectively, were identified in overlay assays of larval thrips proteins resolved by 2-D gel electrophoresis. A total of five proteins were identified from these spots. These interacting proteins might play roles in attachment and entry, endocytosis/exocytosis, and escape from different tissues for transmission to occur. Injection of double-stranded RNA (dsRNA) into adult female thrips triggered an RNAi response that resulted in 23% reduction of the target gene transcript level. This significant reduction resulted in increased mortality and decreased fertility compared to insects injected with control dsRNA or water and non-injected insects as well. The work presented here provides new insights on the molecular basis of this virus-vector interaction and describes new tools to conduct functional genomic assays to study gene function and design control strategies of F. occidentalis.

abstract: Ultrasonication-mediated liquid-phase exfoliation has emerged as an efficient method for producing large quantities of two-dimensional materials such as graphene, boron nitride, and transition metal dichalcogenides. This thesis explores the use of this process to produce a new class of boron-rich, two-dimensional materials, namely metal diborides, and investigate their properties using bulk and nanoscale characterization methods. Metal diborides are a class of structurally related materials that contain hexagonal sheets of boron separated by metal atoms with applications in superconductivity, composites, ultra-high temperature ceramics and catalysis. To demonstrate the utility of these materials, chromium diboride was incorporated in polyvinyl alcohol as a structural reinforcing agent. These composites not only showed mechanical strength greater than the polymer itself, but also demonstrated superior reinforcing capability to previously well-known two-dimensional materials. Understanding their dispersion behavior and identifying a range of efficient dispersing solvents is an important step in identifying the most effective processing methods for the metal diborides. This was accomplished by subjecting metal diborides to ultrasonication in more than thirty different organic solvents and calculating their surface energy and Hansen solubility parameters. This thesis also explores the production and covalent modification of pristine, unlithiated molybdenum disulfide using ultrasonication-mediated exfoliation and subsequent diazonium functionalization. This approach allows a variety of functional groups to be tethered on the surface of molybdenum disulfide while preserving its semiconducting properties. The diazonium chemistry is further exploited to attach fluorescent proteins on its surface making it amenable to future biological applications. Furthermore, a general approach for delivery of anticancer drugs using pristine two-dimensional materials is also detailed here. This can be achieved by using two-dimensional materials dispersed in a non-ionic and biocompatible polymer, as nanocarriers for delivering the anticancer drug doxorubicin. The potency of this supramolecular assembly for certain types of cancer cell lines can be improved by using folic-acid-conjugated polymer as a dispersing agent due to strong binding between folic acid present on the nanocarriers and folate receptors expressed on the cells. These results show that ultrasonication-mediated liquid-phase exfoliation is an effective method for facilitating the production and diverse application of pristine two-dimensional metal diborides and transition metal dichalcogenides. / Dissertation/Thesis / Doctoral Dissertation Chemistry 2018

Submitted by Bruna Rodrigues (bruna92rodrigues@yahoo.com.br) on 2016-09-15T18:05:05Z No. of bitstreams: 1 TeseMSF.pdf: 7415366 bytes, checksum: 7d7fc64462037eda551e93c80b1c66ab (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-16T19:53:31Z (GMT) No. of bitstreams: 1 TeseMSF.pdf: 7415366 bytes, checksum: 7d7fc64462037eda551e93c80b1c66ab (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-16T19:53:45Z (GMT) No. of bitstreams: 1 TeseMSF.pdf: 7415366 bytes, checksum: 7d7fc64462037eda551e93c80b1c66ab (MD5) / Made available in DSpace on 2016-09-16T19:53:53Z (GMT). No. of bitstreams: 1 TeseMSF.pdf: 7415366 bytes, checksum: 7d7fc64462037eda551e93c80b1c66ab (MD5) Previous issue date: 2015-09-24 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Lead (Pb) is a heavy metal widely distributed in the environment, but it does not have any physiological role in the body. Due to its widespread use in the industry, it provides direct contamination of occupationally exposed people and, indirectly, through pollutants for the general. Thus, Pb contamination has become a public health problem. Studies have linked adverse health effects at low levels of Pb in the blood, even at concentrations below 10μg/dL. The effects range from cognitive impairment in children and peripheral neuropathy in adults, but there is little knowledge about its effects in the liver. It has been reported that iron (Fe) has a protective effect that can help in reducing the absorption of Pb in the body. In this sense, the aim of this study was to evaluate the protein profile and morphology in the liver of rats intoxicated by lead acetate (Pb(C2H3O2)2) submitted simultaneously to supplementation with iron sulfate (FeSO4) at 20 mg/Kg body weight. For this, 36 weanling male rats were divided into 6 groups (n=6) and treated for 6 weeks. The control group received deionized water; the first experimental group received deionized water and a solution of FeSO4 every two days; two experimental groups received 100 mg/L Pb(C2H3O2)2 in the drinking water and one of them was supplemented with FeSO4 every two days; two groups received 400 mg/L Pb(C2H3O2)2 in the drinking water, and one of them was supplemented with FeSO4 every two days. After euthanasia, blood samples and liver were collected for the analysis of Pb concentration by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Also, liver samples were collected for proteomic analysis using two-dimensional electrophoresis associated with MS (2D-PAGE-MS) and histomorphological analysis. The concentration of Pb in the blood and liver showed a dose-response effect with a reduction in 40-50% Pb in the groups supplemented with Fe (not significant). Histomorphological changes were observed in all intoxicated groups. Proteomic analysis identified 247 proteins with altered expression in relation to the control group. It was observed a decrease in antioxidant enzymes such as superoxide dismutase, catalase and glutathione peroxidase. The reduction of these enzymes leads to an increase of free radicals in the liver tissue and consequently to an in increase the levels of lipid peroxidation. The peroxidation affects the secretion of lipoproteins, mainly their release from the Golgi complex, which may have contributed to the changes observed in other proteins. The presence of Pb in some spots was confirmed by atomic absorption analysis, and this may have resulted in conformational changes that activate the protein degradation machinery. Based on the results, the present study highlights the deleterious role of Pb in the liver even at low dosage, and although Fe was associated with a reduced absorption of Pb, the results suggest that it should not be used as a prevention strategy to reduce the intoxication by Pb, since itself led to changes in the pattern of protein expression. / O chumbo (Pb) é um metal pesado amplamente distribuído em nosso meio, porém não possui papel fisiológico no organismo. Devido ao seu emprego em diversos setores industriais, proporciona contaminação direta de pessoas ocupacionalmente expostas e, indiretamente, na forma de poluentes à população geral. Por isso tornou-se um problema de saúde pública. Estudos correlacionam efeitos adversos à saúde com níveis baixos de Pb no sangue, até em concentrações abaixo de 10μg/dL. Seus efeitos vão desde o comprometimento cognitivo em crianças a neuropatia periférica em adultos, mas pouco se sabe sobre seus efeitos no fígado. Tem sido relatado que o ferro (Fe) tem um efeito protetor, que pode ajudar na diminuição da absorção do Pb pelo organismo. Neste sentido, o objetivo deste trabalho foi avaliar o perfil proteico e o aspecto morfológico no fígado de ratos intoxicados por acetato de chumbo (Pb(C2H3O2)2), submetidos simultaneamente à suplementação com sulfato ferroso (FeSO4) na dose de 20 mg/Kg de peso corporal. Para isso, 36 ratos machos recém-desmamados foram divididos em 6 grupos (n=6) e tratados por 6 semanas. O grupo controle recebeu água deionizada; o primeiro grupo experimental recebeu água deionizada e uma solução de FeSO4 a cada dois dias; dois grupos experimentais que receberam 100 mg/L de Pb(C2H3O2)2 na água de beber, sendo um deles suplementados com FeSO4 a cada dois dias; dois grupos que receberam a dose de 400 mg/L de Pb(C2H3O2)2 na água de beber, onde para um deles foi administrado simultaneamente FeSO4 a cada dois dias. Após a eutanásia, amostras de sangue e fígado foram coletadas para a análise de concentração de Pb por espectrometria de massas com plasma indutivamente acoplado (ICP-MS). Também foram coletadas amostras de fígados para análise proteômica por meio de Eletroforese bidimensional associada a espectrometria de massas (2D-PAGE-MS) e para análise histomorfológica. A concentração de Pb no sangue e fígado, apresentou um efeito dose-resposta com uma redução em torno 40-50% de Pb nos grupos suplementados com Fe (não significativo). Alterações histomorfológicas foram observadas em todos os grupos intoxicados. Pela da análise proteômica foram identificadas 247 proteínas com expressão alterada em relação ao grupo controle. Foi constatada a diminuição de enzimas antioxidantes como a superóxido dismutase, catalase e glutationa peroxidase. A redução dessas enzimas leva ao aumento de radicais livres no tecido hepático, e consequentemente ao aumento nos níveis de peroxidação lipídica. A peroxidação prejudica a secreção de lipoproteínas, principalmente a liberação a partir do complexo de Golgi, o que pode ter contribuído para alterações observadas em outras proteínas. A presença de Pb em alguns spots foi confirmada através da análise por absorção atômica, e isso pode ter resultado em alterações conformacionais que ativam a maquinaria de degradação proteica. Com base nos resultados, o presente estudo reforça o papel deletério do Pb no tecido hepático, mesmo em baixa dosagem, e apesar de o Fe ter sido associado à redução da absorção de Pb, os resultados sugerem que não deve ser utilizado como estratégia de prevenção para reduzir a intoxicação pelo Pb, já que o mesmo também levou a alterações no padrão de expressão proteica.

Since the scotch-tape isolation of graphene, two-dimensional (2D) materials have been studied with increasing enthusiasm. Two-dimensional transition-metal dichalcogenides are of particular interest as atomically thin semiconductors. These materials are naturally transparent in their few-layer form, have direct band gaps in their monolayer form, exhibit extraordinary absorption, and demonstrate unique physics, making them promising for efficient and novel optical devices. Due to the two-dimensional nature of the materials, their properties are highly susceptible to the environment above and below the 2D films. It is critical to understand the influences of this environment on the properties of 2D materials and on the performance parameters of devices made with the materials. For transparent optical devices requiring electrical contacts and gates, the effect of transparent conducting oxides on the optical properties of 2D semiconductors is of particular importance. The ability to tune the optical properties of 2D transition-metal dichalcogenides could allow for improved control of the emission or absorption wavelength of optical devices made with the materials. Continuously tuning the optical properties of these materials would be advantageous for variable wavelength devices such as photodetectors or light emitters. This thesis systematically investigates the intrinsic structural and optical properties of two-dimensional transition-metal dichalcogenide films, the effect of substrate-based optical interference on the optical emission properties of the materials, and demonstrates methods to controllably tune the luminescence emission of the materials for future optical applications. This thesis advances the study of these materials toward integration in future efficient and novel optical devices. The specific transition metal dichalcogenides investigated here are molybdenum disulfide (MoS2), molybdenum diselenide (MoSe2), tungsten disulfide (WS2), and tungsten diselenide (WSe2). The thickness-dependence of the intrinsic in-plane crystal structure of these materials is elucidated with high-resolution transmission electron microscopy; thickness-dependent optical properties are studied using Raman and photoluminescence spectroscopies. This thesis investigates the optical interference effects from substrates with transparent conducting oxide layers on the optical properties of few-layer MoS2 films. An understanding of these effects is critical for integrating MoS2 into efficient optical devices. We predict contributions of optical interference effects to the luminescence emission of few-layer MoS2 films. The predictions are experimentally verified. We also demonstrate the use of optical interference effects to tune the wavelength and intensity of the luminescence emission of few-layer MoS2. This thesis explores the use of electric fields applied perpendicular to the films to continuously and reversibly tune the band gap of few-layer MoS2 for future variable wavelength devices. To facilitate integration into devices, we demonstrate electric fieldinduced band gap tuning by applying electric fields with a pair of transparent or semitransparent conducting layers, and without the need for direct electrical contact to the MoS2 films. The observed band gap tuning is attributed to the Stark Effect. We discuss challenges to maximizing the effect of electric field-induced band gap tuning. We demonstrate that optical interference effects do not prevent observation of band gap tuning via applied electric fields. We successfully combine two luminescence emission tuning methods: optical interference effects and electric field effects.

Orientador: Sandra de Moraes Gimenes Bosco / Resumo: A pitiose, cujo agente etiológico é o oomiceto Pythium insidiosum, é umadoença que acomete diversas espécies animais, incluindo-se a humana, sendomais prevalente em equinos. A doença é de difícil diagnóstico e tratamento.Estudos sobre a caracterização proteica de P. insidiosum são escassos. Oobjetivo deste estudo foi determinar o perfil proteico de Pythium insidiosum pormeio da estratégia espectrometria de massas e bioinformática, a fim deidentificar fatores de virulência. Para isso, foi padronizada uma técnica deextração de proteínas totais de P. insidiosum, as quais foram quantificadas. Apartir do protocolo de extração de proteínas foi obtido o perfil das proteínasexpressas pelo oomiceto P. insidiosum por meio da análise por eletroforesebidimensional. Os géis analisados apresentaram 186 spots com massamolecular de 12 a 89 KDa, e ponto isoelétrico entre 4-7, destes 103 foramrecortados e sequenciados. Um total de 36 proteínas foram identificadas eagrupadas de acordo com suas funções, seis delas foram classificadas comoproteínas relacionadas à virulência - β 1,3 glucano sintetase, Hsp 70, enolase,peroxirredoxina 2, proteína G e proteassoma unidade β. Os resultados dopresente trabalho contribuirão para o melhor entendimento dos mecanismospatogênicos de P. insidiosum, bem como para novos estudos no campoterapêutico e diagnóstico. / Abstract: Pythiosis, whose etiologic agent is the oomycete Pythium insidiosum, is a disease that affects several animal species, including human, being more prevalent in horses. The disease has difficult diagnosis and treatment. Studies on protein characterization of P. insidiosum are scarce. The objective of this study was to determine the protein profile of Pythium insidiosum by mass spectrometry and bioinformatics strategies aiming to identify virulence factors. To this end, an extraction was standardized technique of total proteins of P. insidiosum, which were quantitated. From the protein extraction protocol it was obtained the profile of proteins expressed by the oomycete P. insidiosum through analysis by two-dimensional electrophoresis. The gels had 186 spots analyzed with molecular weight 12-89 kDa and an isoelectric point of 4-7, 103 of these were cut and sequenced. A total of 36 proteins were identified and grouped according to their functions, six of them were classified as proteins related to virulence - β 1,3 glucan synthase, Hsp 70, enolase, peroxiredoxin 2, G protein and the proteasome β unit. The results of this work will contribute to better understanding of the pathogenic mechanisms of P. insidiosum as well as for further studies in the therapeutic field and diagnosis. / Mestre

O objetivo deste estudo foi avaliar o perfil proteico do plasma seminal equino utilizando eletroforese bidimensional de gel de acrilamida (2D-PAGE) e determinar se algumas das proteínas presentes estavam relacionadas com a congelabilidade do sêmen. O plasma seminal foi coletado de dez garanhões, de alta e baixa congelabilidade de sêmen, provenientes do Haras Estatal da Baixa Saxônia, na cidade de Celle, na Alemanha e rotineiramente utilizados em programas de inseminação artificial. Vinte e cinco bandas proteicas foram encontradas nos géis bidimensionais (12%) e sete delas foram identificadas por MALDI-MS. Das 25 proteínas encontradas nas amostras de plasma seminal dos garanhões, duas bandas proteicas apresentaram densidade óptica superior (P<0,05) nas amostras de garanhões de alta congelabilidade o sêmen: as bandas 5 (80-85 kDa, pI 7,54), que foi identificada como CRISP3 e a 45 (18,2 kDa, pI 5,0-5,2) identificada como HSP-2. Contrariamente a banda 7 (75,4 kDa, pI 6,9 – 7,4), identificada como lactoferrina, a 15 (26,7 kDa, pI 5,51) identificada como calicreína, a 25 (25 kDa, pI 7,54) como CRISP3 e a 35 (13,9 kDa, pI 3,8 – 4,2) que foi identificada como HSP-1, apresentaram valores de densidade óptica superior (P<0,05) nos reprodutores de baixa congelabilidade do sêmen. As proteínas foram identificadas através de espectometria de massa MALDI-MS. As evidências encontradas neste experimento mostram que existem diferenças no perfil proteico dos reprodutores de alta e baixa congelabilidade do sêmen, sugerindo as proteínas CRISP3 e a HSP-2 como possíveis marcadores da alta congelabilidade de sêmen de garanhões. / The objective of this study was to evaluate protein profile of equine seminal plasma using two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and to find if any of these proteins were related to semen freezability. Seminal plasma was collected from 10 stallions of high and low semen freezability routinely used in AI programs from the State Stud of Lower Saxony and Artificial Insemination Center. Twenty five protein spots were identified from the 2 D gel (12%), seven of which were present in all samples. Of the 25 proteins found in the research stallions, two spots showed superior relative content (P<0.05) in seminal plasma samples collected from stallions with high semen freezability: the spots 5 (80-85 kDa, pI 7.54) was identified as CRISP3 and 45 (18.2 kDa, pI 5.0-5.2) was identified as HSP-2. Conversely, the spot 7 (75.4 kDa, pI 6.9 – 7.4) was identified as lactoferrin, 15 (26.7 kDa, pI 5.51) was identified as kallikrein, 25 (25 kDa, pI 7.54) was identified as CRISP3 and 35 (13.9 kDa, pI 3.8 – 4.2) was identified as HSP-1, showed superior relative protein content (P<0.05) on seminal plasma samples from stallions with low semen freezability. The proteins were identified by MALDI-MS. There were differences in the seminal plasma protein profile between stallions with high and low semen freezability. It may be suggested that CRISP3 and HSP-2 may be considered possible seminal plasma markers of high semen freezability.

A finalidade principal deste trabalho é o da obtenção de soluções numéricas de movimento de carga espacial livre em que as grandezas pertinentes dependem de mais de uma coordenada espacial (casos não unidimensionais). Mais especificamente, os problemas estudados versam sobre casos em que um eletródio plano a um dado potencial emite carga não uniformemente ao longo de sua extensão e procura-se obter a deformação das linhas de campo daí resultantes, no espaço até um outro eletródio aterrado disposto paralelamente ao primeiro. Um método baseado em soluções tentativas bem como um outro global usando a \"transformação hodográfica\" recentemente formulada por Budd e Wheeler são apresentados. E também realizado um estudo breve sobre a validade da muito empregada \"suposição de Deutsch\" / The aim of the present work is to obtain numerical solutions of free space charge motion in cases in which the pertinent quantites depend on more than one space coordinate (non uni-dimensional cases). More specifically, the problems under concern here are those in which a plane electrode, at a constant potential, emit charge in a non-uniform way along them and the resultant deformation of the field lines, in the space between it and another plane grounded electrode parallelly disposed, is looked for. A method based on guessed solutions and also a global one using the hodographic transformation recently developed by Budd and Wheeler are presented. A brief study of the validity of the often employed \"Deutsch assumption\" is also carried out

CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel Superior / CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / Dentre os vÃrios microrganismos entomopatogÃnicos utilizados no controle biolÃgico, o Bacillus thuringiensis (Bt) vem sendo considerado uma das alternativas mais viÃveis, devido à presenÃa de proteÃnas inseticidas em seus esporos, como as &#948;-endotoxinas Cry. As toxinas Cry apresentam atividade contra diferentes ordens de insetos, como Coleoptera, Diptera, Hymenoptera, Hemiptera e Lepidoptera. Tais proteÃnas sÃo altamente especÃficas, ou seja, sÃo inÃcuas para a maioria dos organismos nÃo-alvo, fato que favorece sua utilizaÃÃo na agricultura. Hoje existem mais de 114 milhÃes de hectares de lavouras geneticamente modificadas e 37% expressam traÃos de proteÃnas inseticidas de Bt. Como os organismos geneticamente modificados (OGMs) estÃo se tornando cada vez mais predominantes, vÃrias organizaÃÃes internacionais tÃm dado orientaÃÃes no sentido de investigar a seguranÃa de alimentos provenientes de OGMs. Este trabalho teve como objetivo utilizar uma abordagem toxicoproteÃmica para anÃlise de risco da proteÃna recombinante Cry1Ac de Bt a fim de contribuir para uma maior compreensÃo de seus efeitos em modelo de mamÃferos. O ensaio de toxicidade foi conduzido de acordo com o protocolo 425 da âOrganizaÃÃo para a CooperaÃÃo e Desenvolvimento EconÃmicoâ - OECD e nÃo foram verificadas mortes ou sinais de toxicidade. As anÃlises proteÃmicas baseadas em gel mostraram 4 proteÃnas diferencialmente expressas Serpina &#945;-1, Serpina A3K, CininogÃnio e Complemento C3. Essas proteÃnas tiveram uma reduÃÃo em sua expressÃo no grupo tratado com a toxina Cry1Ac. Na abordagem âgel-freeâ foram identificadas 7 proteÃnas diferencialmente expressas. Dentre elas, fator I, inibidor de tripsina H3, plasminogÃnio, serpina A6, albumina e proteÃna resistente à oxidaÃÃo apresentaram uma expressÃo maior em animais tratados com Cry1Ac, enquanto que a protrombina teve sua expressÃo reduzida em animais tratados com a mesma proteÃna. Tais molÃculas sÃo importantes para hemostasia e sistema imune, podendo interferir no processo inflamatÃrio, na ativaÃÃo da via do complemento e da cascata de coagulaÃÃo. No entanto, a abordagem toxicoproteÃmica adotada mostra-se Ãtil para a identificaÃÃo de efeitos adversos, atà mesmo de uma jà amplamente conhecida por sua baixa toxicidade. Isso encoraja a utilizaÃÃo da referida abordagem para a avaliaÃÃo de risco de proteÃnas recombinantes. Apesar das alteraÃÃes fisiolÃgicas causadas, a proteÃna Cry1Ac ainda à considerada segura jà que tais alteraÃÃes ocorreram na dose mais alta recomenda pela OECD (2000mg/Kg) e sem causar morte dos animais. / Among the various pathogenic bacteria used in biological control, Bacillus thuringiensis has been considered one of the most viable alternatives, due to the presence of insecticidal proteins in their spores, such as the &#948;-endotoxin, Cry. The Cry toxins exhibit activity against different insect orders, such as Coleoptera, Diptera, Hymenoptera, Hemiptera and Lepidoptera. Such proteins are highly specific, which means, they are harmless to most organisms. This fact justifies their use in agriculture. Nowadays, there are over 114 million hectares of GM crops and 37% express traits of insecticidal proteins of B. thuringiensis. Since genetically modified organisms (GMOs) are becoming increasingly prevalent, several international organizations have given guidelines to investigate the safety of food derived from GMOs. This work aimed to evaluate the acute toxicity of the entomotoxin Cry1Ac in rats through classical in vivo analyzes associated with proteomic study by two-dimensional electrophoresis and shotgum proteomic technique (gel-free). Toxicity tests were conducted according to the protocol of 425 "Organization of Economic Cooperation and Development" - OECD and no deaths or signs of toxicity were observed. The gel-based proteomic analysis showed four differentially expressed proteins: Serpin &#945;-1, Serpin A3K, Kininogen and Complement C3. These proteins expressions were reduced for the group treated with the Cry1Ac toxin. In gel-free approach, seven differentially expressed proteins were identified. Among them, factor I, H3 trypsin inhibitor, plasminogen, serpin A6, albumin, and protein resistant to oxidation showed a higher expression in animals treated with Cry1Ac, while the prothrombin expression was reduced in animals treated with the same protein. Such molecules are important for hemostasis and immune system, and may interfere with the inflammatory process, activation of the complement pathway and the coagulation cascade. Despite the physiological changes caused by Cry1Ac, this protein is still considered safe since these changes occurred at the highest dose recommended by OECD (2000 mg / kg) and without causing death of the animals.